Catenda Hub screenshot of an issue with a too small door in a construction

Slash 80% of your emails with the BIM Collaboration Format (BCF)

Catenda Team

Open BIM encompasses both a set of workflow and software tools to ensure efficient and reliable construction processes. 

By Sylvain Marie, Catenda

The need for a BIM Collaboration Format

A major component of open BIM is IFC (Industry Foundation Classes), the ISO standard to exchange building modeling designs. Collaborating by exchanging full IFC files is not practical. Let’s see how BCF, another open BIM standard can support collaboration workflows with lightweight data exchanges.

Let’s compare IFC to PDF (Portable Document Format) in the office world (of course, IFC goes further than a 2D or 3D view of the project thanks to its embedded semantics, but let’s consider this for the sake of the argument). Both are ISO standards meant to exchange data in a neutral way in order to enforce interoperability between software. Both are great for deliverables, for sign-offs, etc.

But what if we need to converse, comment, request specific information, or relate to specific objects when we are not sitting in the same room at the same time? The same way PDF doesn’t define how document revisions and comments should be exchanged, collaboration and communication workflows were left out of the scope of IFC, on purpose. IFC was meant to convey self-contained data models and it does not address the need to exchange information relating to a specific project sub-part, like RFI (Requests For Information), sequencing coordination or issues occurring during the project lifecycle.

buildingSMART went the extra mile and worked on defining such a standard to guarantee a neutral way of exchanging questions, comments, issues on IFC files.

What is BIM Collaboration Format

BIM Collaboration Format (BCF) is an open standard to exchange BIM-related issues between software. BCF could be seen as a “Post-It® system for IFC”, or more accurately a “Post-it® threading system for IFC” thanks to its user assignation and status management.

BCF messages link messages to IFC entities. These messages can be assigned to a user and have status.

BCF lets users exchange issues on construction projects from different software. An issue is composed of a topic, some markup (a collection of textual information related to the topic, like a name, comments, a status), a viewpoint to provide spatial information to the topic, and a snapshot taken from the viewpoint. References to documents stored on the BCF server can be added. Catenda Hub (previously Bimsync) provides several extensions to the standard, like references to objects in the BIM project in order to facilitate their selection and inspection.

Here is how BCF issues can be visualized in Catenda Hub (previously Bimsync):


BCF: one format, two flavors

The initial BCF data format has been defined to be stored in a zipped directory containing files stored in XML (for the BCF data) and PNG (for the snapshot). As sending ZIP files in emails was not the most efficient collaboration process, buildingSMART soon focused on providing an API to enable servers to exchange BCF data structures instead of spamming inboxes.

We now have two compatible standards to exchange BCF tickets: BCF-XML — using files to store collaboration information and BCF-API — using API calls between servers to exchange collaboration information. Servers implementing the BCF API can optionally also host the models.

BCF standard management

BCF is developed by buildingSMART members and can be openly followed on GitHub

Catenda is actively participating in the core developer’s efforts to set and develop the BCF standard. Here is the evolution of the BCF format over time:

BCF Timeline

How BCF is used in open BIM?

BCF has initially been implemented in Tekla and Solibri solutions. Soon after, Catenda Hub (previously Bimsync) adopted BCF for its issue management workflow. Graphisoft and other BIM software vendors followed.

Thanks to the very flexible format, BCF can even be used in software which doesn’t rely on IFC, thanks to plugins developed for closedBIM authoring tools.


The BCFier project adds BCF support for Revit.

We at Catenda even use BCF for our own software development projects!

Using BCF in Revit thanks-to the BCFier open source project

Using BCF in construction projects

Many actors are involved in construction projects, and several milestones must be met to deliver projects on time and on budget. Powerful workflows for information exchange are crucial at every stage and will be tailored for specific actors and phase requirements.

BCF for design coordination

During the design phase, architects can easily address requests for information from other designers.

For instance, accessibility regulations can be checked by certification agencies by precisely mentioning which element needs a closer look. In this example, Dag as the certification agency tags an element in the model and opens a BCF issue assigned to Michael the architect to log a change request. The exact point of view used to pinpoint the issue can be recreated, offering the architect a clear context to resolve the issue.

Interactive and online discussion-between-architects-and-engineers to solve layout issues in Bimsync

The two professionals can add comments, related documents or labels to the issue.

When the architect has resolved the issue, a new model revision is uploaded in Catenda Hub (previously Bimsync) and a notification is sent to all involved parties. If the issue is resolved, it can be closed.

Managing several thousand issues for the full project lifecycle is possible thanks to automatic dashboards grouping issues by status, labels, due date or involved personnel:

BCF issues can be filtered and listed with multiple order criteria in Bimsync

BCF for construction in the field

Catenda Hub (previously Bimsync) is more than the well-known user interface; it is also a software platform exposing a fully BCF compliant issue management system. Several software integrators use the Catenda Hub (previously Bimsync) BCF API to develop their own field applications. Stay tuned as we will soon have some announcement on this topic!

BCF for Maintenance and Operations

BCF is now also used in the maintenance & operations phase. For instance, Legendre, one of our integration partners, just announced a new solution to manage buildings and their inhabitants. The new MaXim application internally uses BCF issues from Catenda Hub (previously Bimsync).

Preview screens of MaXim the upcoming Operations Maintenance online application from Groupe Legendre

The future of BCF

BCF is an evolving standard, and many vendor-specific extensions are currently deployed. Catenda Hub (previously Bimsync) offers a number of powerful extended features, all meant to be published in a forthcoming version of the standard.

BCF dashboards are BCF issues grouped under a common theme. Several extensions are currently offered:

  • Custom issue types
  • Custom issue statuses
  • Project members emails can be listed to be used in issues

Also, BCF topics extensions include:

  • linking objects to BCF issues. IFC objects are identified by their Globally Unique IDentifier (GUID).
  • linking 3D locations to BCF issues. Sometimes IFC objects are not precise enough and a specific location is required to better support the BCF issue.

From an industry standard to an ISO standard?

BCF is an industry-standard and helps software enable interoperable information workflows. Information exchange in construction projects already benefits from the ISO 29481 IDM (Information Delivery Manual) standard. Assessing that BCF complies with this ISO standard will help spread its usage even further when quality management implies a comprehensive adoption of ISO standards. Discussions in the buildingSMART association are underway to define BCF as an ISO 29481 compliant standard.

Software interoperability

As one of the core developers of BCF-API, Catenda Hub (previously Bimsync) has immediately deployed the new specification as its issue management workflow in 2015, becoming the first BCF server.

Since then, several software vendors have implemented BCF-XML, which offers “offline” support for issues management. We are glad to welcome BIMCollab as the latest entry in the BCF-API compliant software list! We welcome other software vendors to join us in adopting open standards for collaboration in the construction industry.